Failure Mechanisms and Accelerated Life Tests of Nickel-Cadmium Batteries.
Annual technical rept. no. 1, 1 May 69-30 Apr 70,
BATTELLE MEMORIAL INST COLUMBUS OH COLUMBUS LABS
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The report describes the experiments planned to verify the gradient hypothesis all aging is caused by intensity gradients with their associated strains and strain rates as an approach to valid accelerated life testing of nickel-cadmium batteries. The stresses identified for the aging of sealed batteries are 1 temperature gradients, 2 voltage gradients, 3 concentration gradients, and 4 pressure gradients. Plans to develop nickel-cadmium cells with longer life because of decreased intensity gradients are also described in the report. A mathematical model based on springs and dashpots is being developed as an analogy of how stresses, strains, and strain rates can be combined to describe the performance of any energy storing device such as a battery. Aging will then be associated with the time rate, or cycle rate, of change of the proportionality constants in the spring and dashpot combination. Data from continuing simulated orbital life tests are reported for later analysis and discussion. Also, cell component thermal conductivity measurements are reported and discussed. Then, literature values for thermal conductivities and resistivities of nickel-cadmium cells are compared with measured values for cells and with values predicted for the cells from measured components. Author
- Electric Power Production and Distribution